From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34CFDC43219 for ; Tue, 30 Apr 2019 09:18:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 055C120652 for ; Tue, 30 Apr 2019 09:18:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726832AbfD3JSu (ORCPT ); Tue, 30 Apr 2019 05:18:50 -0400 Received: from mga06.intel.com ([134.134.136.31]:4844 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725938AbfD3JSu (ORCPT ); Tue, 30 Apr 2019 05:18:50 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Apr 2019 02:18:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,413,1549958400"; d="scan'208";a="146944618" Received: from shbuild888.sh.intel.com (HELO localhost) ([10.239.147.114]) by orsmga003.jf.intel.com with ESMTP; 30 Apr 2019 02:18:46 -0700 Date: Tue, 30 Apr 2019 17:22:48 +0800 From: Feng Tang To: Peter Zijlstra Cc: Andrew Morton , Arjan van de Ven , Jonathan Corbet , Ingo Molnar , Eric W Biederman , Dmitry Vyukov , Thomas Gleixner , Andy Lutomirski , Ying Huang , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/3] latencytop lock usage improvement Message-ID: <20190430092248.b7ztl733nhu7acjd@shbuild888> References: <1556525011-28022-1-git-send-email-feng.tang@intel.com> <20190430080910.GI2623@hirez.programming.kicks-ass.net> <20190430083505.n5mozwybbnwydo3z@shbuild888> <20190430091033.GN2623@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430091033.GN2623@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On Tue, Apr 30, 2019 at 11:10:33AM +0200, Peter Zijlstra wrote: > On Tue, Apr 30, 2019 at 04:35:05PM +0800, Feng Tang wrote: > > Hi Peter, > > > > On Tue, Apr 30, 2019 at 10:09:10AM +0200, Peter Zijlstra wrote: > > > On Mon, Apr 29, 2019 at 04:03:28PM +0800, Feng Tang wrote: > > > > Hi All, > > > > > > > > latencytop is a very nice tool for tracing system latency hotspots, and > > > > we heavily use it in our LKP test suites. > > > > > > What data does latency-top give that perf cannot give you? Ideally we'd > > > remove latencytop entirely. > > > > Thanks for the review. In 0day/LKP test service, we have many tools for > > monitoring and analyzing the test results, perf is the most important > > one, which has the most parts in our auto-generated comparing results. > > For example to identify spinlock contentions and system hotspots. > > > > latencytop is another tool we used to find why systems go idle, like why > > workload chose to sleep or waiting for something. > > You're not answering the question; why can't you use perf for that? ISTR > we explicitly added support for things like that. I was not very familiar with perf before. And after my last reply, I googled a little, and found "perf sched latency" has the simliar function, except I can't directly get the call chain, any suggestion for this? thanks! - Feng